Generally, there is a weight standard for luggage to be carried on a plane or a train to limit the total weight of the luggage. Therefore, more and more consumers will select a suitcase with light total weight and large supporting power, so as to put more articles in the luggage and to meet the weight standard of the luggage.
As shown in FIG. 1, the existing lightweight suitcase on the market mainly comprises a case framework 1 and case material coated outside the case framework 1. In order to reduce the weight of the suitcase, the case framework 1 comprises connecting rods 2, three-way connectors 3, four-way connectors 4 and pull rods 5, wherein the connecting rods 2, the three-way connectors 3, the four-way connectors 4 and the pull rods 5 are spliced together to form the case framework 1; then wheels 6 and supporting legs 7 at the bottom part of the suitcase are respectively connected with the bottom part of the case framework 1; the pull rods 5 are fixed in the case framework 1 through cover plates 8; and the case material coated outside the case framework 1 tightly combines every part of the case framework 1 into a whole body.
Although the case framework 1 of the existing suitcase is light, its fastness needs to be improved, because the connecting rods 2, the three-way connectors 3, the four-way connectors 4 and the pull rods 5 are connected to one another. For example, the three-way connectors 3 and the four-way connectors 4 for connecting the connecting rods 2 are not firm enough and can easily break.
Meanwhile, as the case framework 1 comprises the connecting rods 2, the three-way connectors 3, the four-way connectors 4 and the pull rods 5, which are connected to one another. When the case material is coated, lining boards 9 are required to be arranged on the two sides of the upper part of the case framework 1 to ensure that the case material be coated more tightly on the case framework 1. In addition, the pull rods 5 of the suitcase adopt traditional extension pull rods without locking pieces. The positions of the pull rods 5 cannot be adjusted freely, and as a result, the use of the suitcase is inconvenient, and the suitcase cannot be pushed to move forward through the pull rods 5.
FIG. 2 shows the pull rod structure of another suitcase, wherein pull rods 2′ are arranged in the center position of the rear part of a case framework 1′; the middle parts of the pull rods 2′ are sleeved in an upper cover plate 21′; the pull rods 2′ are fixed on the case framework 1′ by connecting the pull rods 2′ with the upper cover plate inner lining 22′ arranged in the center position of the rear part of a case framework 1′; the bottom parts of the pull rods 2′ are fixed at the bottom part of the case framework 1′ through a lower base; the extension of the pull rods 2′ is realized by stretching pull rod inner tubes 24′ in pull rod outer tubes 25′. However, the pull rods 2′ are still not provided with locking pieces, the positions of the pull rods 2′ can not be adjusted freely. Therefore, the use of the suitcase is inconvenient, and the suitcase cannot be pushed to move forward through the pull rods 2′.